| It's fun to think about. There's advantages both ways, but I think it leans most-heavily towards keeping AC. 1. One of these is simplicity. With AC, one single home run of cabling (eg, Romex) can feed a whole room full of stuff, like a bedroom or a living room. At one end of the run is a circuit breaker (a fairly simple electromechanical device) and at the other end is a series of outlets (which are physically daisy-chained, but are functionally just wired in parallel with eachother). Since one single run of cable can feed many devices, it is easy to accomplish. 2. Another advantage is that it is universal. Anything can plug into these outlets. Whatever a person brings into the home to use, they can plug it into an outlet and it works. It works this same way in every home. 3. And there's quite a lot of power available: A common 20A 120v branch circuit cabled up with 12AWG Romex is stated to supply up to 16A continuously, or 1920W. For intermittent loads, it can supply 20A -- or 2400W. That's tiny by European standards, but it's still quite a lot of power. It's plenty to run a space heater when Grandma visits and she complains about the guest room being cold (even as you start to sweat when you cross the threshold to investigate) and a big TV and a whole world of table lamps, all at once. And you can plug this stuff into any outlets in a room, and it Just Works. 4. But, sure: Lots of devices want DC, not AC. So there's a necessary conversion step that is either integral to the device being plugged in, or in the form of the external wall warts we all know very well. So let's compare to power-over-ethernet. 1. It's also simple, but only tangentially-so. One home-run cable per outlet, whether that outlet is used or not, is something that can be rationalized as being a simple topology. A PoE switch at the head-end instead of a central box with circuit breakers is a simple-enough thing to transition to. And a lot more individual cables are required, but they're relatively small and are generally easier to install. 2. It's standardized, but it's not universal at all. I've got a few PoE widgets around the house, but I'm pretty friggin' weird when it comes to what I do with electricity. I can't go to Wal-Mart and buy more PoE widgets to use at home, and when people visit they aren't bringing PoE adapters to charge their phones and other electronics. My computer monitor doesn't have a PoE input. I can easily imagine a table lamp or a fan that connects to PoE, and also uses it as a network connection for automation, and that sounds pretty sweet in ways that tickle my automation bones in the most filthy of fashions... but that's getting even further into the weeds compared to how regular people expect to do regular things. 3. There isn't a lot of power available. 802.3bt Type 4 is the highest spec. And within that spec: While switch ports can output up to 100W, a device being powered is limited drawing no more than 71.3W. Now, sure, that's 71.3W per port, but in a room with 10 ports that's still only ~700W -- at most -- in that room. And Grandma's space heater won't run on 71.3W, nor her electric blanket. My laptop wants more than this. The list of useful, portable things that we casually plug into a wall that only draw less than 71.3W is pretty short and most don't benefit from the main advantage of PoE, which is a combination of [some] power alongside high-speed Ethernet data. 4. We still need wall warts since PoE is nominally ~48VDC. For example: Phones use less than 71.3W while charging, but they don't run on 48V. That means 120V AC comes in from the grid, gets shifted to 48VDC for distribution within the dwelling, and then gets shifted yet again to the produce the power (5, 9, 15, and 20V are common-enough in USB PD world) that devices actually want. That's more lossy conversion steps, not fewer -- and we still get to keep the extra conversion (wall warts) as punishment for our great ideas. This is not the path towards increased energy efficiency. --- PoE is great for the things we use it for today. A camera, a wireless access point -- you know, fixed-location stuff that uses networked data as its primary function and also requires power. Installed PoE light fixtures (like, say, task lights in a kitchen) also sounds neat -- unless they die prematurely and no PoE replacements are to be found. (Now, you have not just one or two problems, but many: The lights aren't working in that space and they can't be replaced with a trip to Lowes because the Romex that would normally have been installed was deliberately deleted from the plan. It could have been a 20-minute DIY fix that costs less than $100, but now it involves drywall and paint and retrofitting new cabling. Or maybe PoE replacements do exist, but it's now 2035 and the new ones don't talk the same network protocols as the old ones did.) But there are other upsides: I've got an 8-port PoE-powered network switch that works a treat. It's a dandy little thing. And it sure would be neat to plug my streaming box in with PoE and kill two birds with one cable; I would like that very much. But most people? Most people don't give a damn about ethernet (PoE, or not!) these days, or streaming boxes, and that trend is increasing. They just plug their lamp into the regular outlet on the wall like they always have, and deal with whatever terrible UI is built into their smart TV, and use wifi for anything that needs data. And when they buy a home that is filled with someone else's smart infrastucture, their first task (more often than not) is to figure out who to call to erase those parts completely and put it back to being normal and boring. |